Stop mechanism for drill presses



July 20, 1954 0. LEGGETT 2,683,998

STOP MECHANISM FOR DRILL PRESSEIS Filed June 11, 1953,

INVENTOR GUY o. LEGGETT Patented July 20, 1954 UNITED STATES PATENT OFFICE 4 Claims. 1

This invention relates to a stop mechanism for drill presses.

It is an object of the invention to provide a stop mechanism for drill presses which will provide a simple arrangement for stopping the operation of the drill upon the same arriving at the desired depth of hole in the work piece and wherein the gauge means provided therewith is easy to adapt and adjust for the desired. hole depth.

It is another object of the invention to provide in a stop mechanism for a drill press an adjustable abutment that cooperates with a spring case forming a part of a stop mechanism whereby to provide a find adjustment of the depth of hole after the depth has been selected by the handle and whereby the drill press is adapted for doing fine and accurate drilling work.

It is another object of the invention to provide a stop mechanism for a drill press wherein upon reaching the end of the drilling operation the turn of the handle throws over center ball elements serving to move the handle .hub axially and cause engagement with a spring case with which the screw for fine adjustment of the depth is associated.

Other objects of the invention are to provide a stop mechanism for drill presses having the above objects in mind, which is of simple construction, inexpensive to manufacture, has a minimum number or". parts, automatic in operation, easy to adjust and eficient in operation.

For other objects and for a better understanding of the invention, reference may be made to the following detailed description, taken in connection with the accompanying drawing in which Figure 1 is a fragmentary elevational View of a drill press head with a portion of the same broken away to show the features of the present invention;

Fig. 2 is a transverse sectional view taken on line 22 of Fig. 1;

Fig. 3 is a transverse sectional view taken on line .i-v of Fig. 1;

Fig. 4 is a fragmentary enlarged longitudinal sectional view taken on line 4-4 of Fig. 1 and looking upon the over center ball connections between the thrust plate and the handle hub;

Fig. 5 is a collective and exploded perspective view of the thrust plate and the handle hub to show the construction thereof;

Fig. 6 is a fragmentary side elevational view of the scale to show the manner in which it is connected upon the upstanding rod carried by one of the drill press parts.

Referring now to the figures, iii represents a drill press head having a vertical opening ll therein through which a rack l2 extends. On the lower end of the rack there is mounted a drill chuck i 3 and a plate It to which is connected an upstanding pointer rod l5 having a pointer portion IS.

The press head it! has a transversely extending opening I? in which there may be rotated a rack pinion shaft 13 that meshes with the teeth of rack i2. This shaft 18 has a head or en1argement ii) that engages with the side of the press head is. This shaft [8 is splined and a handle hub 29 is slidably secured thereto by a spline key 2 I. Accordingly the handle hub 26 can slide along the shaft 18.

A transverse bar 22 is secured to the lower face of the drill head Ill and has an upstanding rod 23 threadedly secured thereto and locked by nuts 26 and 2.5, Fig. 2. This rod 23 carries a scale 26, Figs. 1 and 6, which is spring pressed by a leaf spring 2'! to hold its ends 28 and 2:? in tight frictional engagement to the rod 22 so that the scale can be adjusted to any location on the rod and held tight against movement. This scale is graduated to indicate the depth to which the hole is to be drilled. Y

To set the scale 25, a drill element is placed in the chuck i5 and the point of the same is brought to the work surface by the turning of the handle hub 20 and the rack shaft it. Thereafter the scale 26 is struck down on the rod 22 so that the pointer portion 36 of the rod 55 which would have been adjusted downwardly with the chuck is aligned with the zero location on the scale. The downward movement of the drill element into the work continues from this zero indication and the operator observes the scale to determine the depth to which the drill element is to be extended into the work piece.

Surrounding the head it at one end thereof is a spring case 3! having a coil spring 32 anchored to the case as indicated at 33 and to the head In as indicated at 34. This spring case has teeth 34a. adapted to engage with teeth 35 on the hub 20 being actually moved along the spline key 2| and shaft [8.

Extending outwardly from the hub 20 are ha-ndle arms 31 having respectively round balls 38 on the outer end of the same. These handle arms are journaled in the hub and extend radially therefrom a-t angularly spaced locations thereon.

The end of the hub 25 has an annular groove 39 therein into which the handle rods 3'! extend. The handle rods turn in the openings provided in the hub 20. Each handle rod has an over center ball element 40 connected by its threaded shank 4| with the handle rod 31. This ball 40 extends out of the groove 39 and into one of three notches 42 in an annular projection 43 of a thrust plate 44. This thrust plate 44 can be adjusted along the shaft I8 and is held in its adjusted position by a nut 45 on threaded portion 46 of shaft [8 and a set screw 41.

Fixed on the head I is a knob 48 into which is threaded an adjusting abutment or screw 49 having a dial or knob 50 thereon. This abutment 49 can be adjusted so as to accurately locate the depth of the hole to be cut and to cause further movement of the drill element and of the handle hub 20 when the bottom of the hole has been drilled. The spring case 3| has a projection 52- extending radially therefrom for engagement with the adjusting screw 49 when the bottom of the hole has been reached. A very fine adjustment can be had with this abutment screw 48.

As the drilling begins, the handle hub is turned by the handle rods 3'! and the ball elements 4! will bear against the thrust plate in such a manner as to cause the handle hub 20 to have its teeth engage with the teeth 34a of the spring case 3! whereby the spring case will be turned against the action of its spring. Upon arriving at the abutment by the projection 52 the hole will be drilled to the accurate depth. While this operation is being formed the pointer I6 is watched relative to the scale indications upon scale 26. The teeth on the hub 28 meshing with the teeth on the spring case limits any further downward movement as the projection on the spring case abuts the screw 49. When the operator reverses the action of the handle, thrust spring 55 lying within grooves in the opposing ends of the handle hub 20 and of the spring case will separate the handle hub from the spring case so as to allow the spring case to return to its original position under the action of its spring 32. Upon starting another drilling operation the balls 40 will again be placed overcenter so that the hub 20 will have its teeth 35 engage with the teeth 34 of the spring case.

It should now be apparent that there has been provided a convenient and accurate stop mechanism for drill presses.

While various changes may be made in the detailed construction of this stop mechanism, it shall be understood that such changes will be within the spirit and scope of the present invention as defined by the appended claims.

What is claimed is:

1. A drill press having a head, a vertically extending rack adjustable through the head and having a drill chuck attached thereto, a rack shaft engageable with the rack and a handle hub splined to the rack shaft for axial adjustment thereon, a spring case journaled on the head and having teeth thereon, said handle hub having teeth adapted to engage the teeth of the spring case upon the handle hub being adjusted axially on the rack shaft, a projection on the spring case and stop means on the press head engageable by the projection of the spring case upon the hole being drilled to its predetermined depth.

2. A drill press as defined in claim 1 and said stop being adjustable to adjust to fineness the location of the hole being drilled, said spring case having a spring reacting between the case and the press head to effect the return of the spring case to its starting position and spring means disposed between the handle hub and the spring case and press head to normally urge the handle hub out of engagement with the spring case.

3. A drill press as defined in claim 1 and said handle hub having handle rods extending radially therefrom and journaled in said hub, said handle hub having an annular groove into which the handle rods extend, over center ball elements mounted respectively within said annular groove in the handle hub, a thrust plate having an annular projection extending into the annular groove of the hub with angularly spaced notches for respectively receiving the over center ball elements on the handle rods and adjustable nut means on the rack shaft for adjustably retaining the thrust plate upon the shaft, the movement of the handle hub causing over center movement of the ball elements and the engagement of the handle hub with the spring case, the reverse movement of the handle hub permitting release of the handle hub from the spring case.

4. A drill press as defined in claim 1 and an upstanding pointer rod connected to the vertically adjustable rack bar, a scale rod extending vertically and parallel to the pointer rod fixed References Cited in the file of this patent UNITED STATES PATENTS Name Date Tautz l- Mar. 8, 1938 Number 

